Steps to reproduce:
1. Download attached project
2. Build and run to WP8.1
3. Exception will be thrown:
A first chance exception of type 'System.DllNotFoundException' occurred in Assembly-CSharp.DLL
Exception: Unable to load DLL 'WP81NativePlugin.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
Type: System.DllNotFoundException
Module: Assembly-CSharp
InnerException: <No Data>
AdditionalInfo:<No Data>
at Useit.GetHelloWorldString()
at Useit.Start()
at Useit.$Invoke1(Int64 instance, Int64* args)
at UnityEngine.Internal.$MethodUtility.InvokeMethod(Int64 instance, Int64* args, IntPtr method)

(Filename: C:/buildslave/unity/build/Runtime/Scripting/WinRTUtility.cpp Line: 87)